Well first off, you're never going to get "better" mileage running 87. It isn't going to happen. You may (and I stress MAY) end up paying slightly less per mile for 87, but it's likely going to be less than a cent per mile. Are you really going to sit there and tell me that a fraction of a cent per mile isn't worth the increased hp/torque? Here's a cost vs performance equation to consider: 91/93 octane will cost you $0.31/mile and provide you with 411hp and 87 octane will cost you $0.31/mile and provide 400 (or less) hp. So which one would be the better choice? Price per Gallon DOES NOT EQUAL Price per Mile! Price per mile is the only cost that matters when determining how much you're spending on your vehicle for fuel.
Secondly, when did I ever say anything about running race fuel, or e-85 for that matter? I've never run either and never claimed to know anything about them whatsoever. The vehicle is not certified by ford to run either fuel types. Whether or not you choose to follow that is up to you. Some will say it's perfectly fine (with a correct tune) others will say it could be extremely risky. That's a whole can of worms (and several hundred pages worth of already existing argument) I'm not going to get into here. Do what you want there. All I was getting at is that you seemed to be more concerned about your cost per tank, which has little to do with your actual fuel economy. You want to put a SC in and run E-85 through it and if you end up with a lower fuel bill at the end of the year, great! The fact is, a SC generally doesn't lower your fuel costs (e-85 not withstanding, since not that many, that I know of, run it in there SC'd Raptors).
Of course a tune is going to help a lot, but are you trying to compare an economy tune for 87 to the factory tune when running 93, or what? (Thats apples to oranges) A custom tune for 87 versus a custom tune for 93 is going to show you the same performance differences that you would see between the two fuel types at stock.
For example:
Stock tune 87=12mpg, 93=14mpg
Custom tune 87=13mpg, 93=15mpg.
So again, even towing on a flat grade, how are you possibly going to get better economy running 87 versus 93? Tune or not?
Don't believe me? Do an experiment for yourself. Download the
Car Care fuel/maintenance tracker app
and use it to track your fuel and costs. Start by tracking 5-6 tanks worth of 87 then switch to 93 and track another 5-6 tanks. Then go into the vehicle stats and read the results for yourself.
I'm not trying to be an ******* or anything, but it really seems like you're not understanding what I'm saying. There are no positives to running 87 when compared to 91/93. On the rare occasion where 87 would work out to be cheaper per mile than 91/93 (which isn't very often), well, that begs the question, why aren't you running 89(10%ethanol) Then? Not sure how the prices are for it in Miami, but here it's almost always $0.10 or so cheaper per gallon than 87 and gives a fuel economy mid way between 87 and 91/93. That easily makes it the most cost effective fuel of the three basic readily available types. You don't want to throw your money out the window? Then why aren't you running 89?
